While chronic conditions such as heart disease, stroke, cancer, diabetes, obesity, and arthritis are on the rise, these can be controlled by improving lifestyles.

In that vein, the Swiss Federal Office of Public Health (FOPH) is in the process of developing a national prevention strategy with a view to improving the population’s health competence and encouraging healthier behavior.

Researchers from the University of Zurich examined the effects of tobacco smoking, an unhealthy diet, physical inactivity, and harmful alcohol consumption — both individually and combined — on life expectancy.

For the first time the consequences of an unhealthy lifestyle can be depicted in numbers. An individual who smokes, drinks a lot, is physically inactive, and has an unhealthy diet has a 2.5-fold higher mortality risk in epidemiological terms than an individual who looks after his health.

For the study, the researchers used data from the Swiss National Cohort (SNC) correlating data on tobacco consumption, fruit consumption, physical activity, and alcohol consumption from 16,721 participants aged between 16 and 90 from 1977 to 2008.

The impact of the four forms of behavior was still visible when biological risk factors like weight and blood pressure were taken into account as well.

“The effect of each individual factor on life expectancy is relatively high,” said Martin-Diener.

But smoking seems to be the most harmful. Compared with a group of non-smokers, smokers have a 57 percent higher risk of dying prematurely.

The impact of an unhealthy diet, not enough activity, and alcohol abuse results in an elevated mortality risk of around 15 percent for each factor.

“We were very surprised by the 2.5 fold higher risk when all four risk factors are combined,” said researcher Brian Martin.

Hence, the probability of a 75-year-old man with all risk factors surviving the next 10 years is, for instance, 35 percent, without risk factors 67 percent — for a woman 47 and 74 percent respectively.

According to Martin, an unhealthy lifestyle has above all a long-lasting impact.

Whereas high wine consumption, cigarettes, an unhealthy diet, and physical inactivity scarcely had any effect on mortality among the 45 to 55-year-olds, it does have a visible effect on 65 to 75-year-olds.

The probability of a 75-year-old man with none of the four risk factors surviving the next ten years is 67 percent, exactly the same as the risk for a smoker who is 10 years younger, doesn’t exercise, eats unhealthily and drinks a lot.

Researchers plan to develop visual charts (survival charts) to show life expectancy and the influence of four risk behaviors for the age groups in what are known as survival charts.

The impact of individual risk factors and their combined effect on mortality will be visible at a glance.

“In future, doctors will be able to refer to the easily comprehensible charts when giving health counselling to their patients in primary care,” said Martin-Diener.